A point mutation was introduced into exon 4 to change alanine codon 474 to threonine (p.A474T). The loxP site flanked neomycin resistance gene cassette that was inserted into intron 3 was removed via Cre-mediated recombination in ES cells prior to blastocyst injection. This mutation causes a defect in GRE-mediated transactivation and prevents dimerization. (J:67720, J:121199)